Pyrazolone monoazo dyestuffs



Patented Apr. 7, 1953 UNITED sures rs; oFFICE 'I'YBA'ZOLONE MONOAZO DYESTUFFS fians-Frank .Piepenbrink, .Leverkusen-Wiesdorf,

and Otto Bayer, Loverkusen-Bayerwerk, Germany, assignors toFarbenfabriken Bayer, Leverkusen, Germany No Drawing. ApplicationOctober 2, 1951,8erial No. 249,398. In "Germany October 19, 1950 l l Thepresent inventlonrelatss to new .monoazo dyestuffs andto a processofomaking these dyestuffs; more particularly it relates to monoazodyestufis of the general formula:

- obtained into the corresponding esters by saponifying the nitrilegroup and esterifying the carboxyl group formed thereby. It is ofadvantage to carry out saponification and esterification in one processby heating one mole of dyestufi with a mixture of 2-10 moles of alcoholand one mole of sulfuric acid for several hours to loo-200 C. Mostly thedyestufi esters are obtained in a quantitative yield.

These dyestuff esters may also be obtained by first converting thel-cyanoalkyl pyrazolones into the corresponding carboxylic acids by saponification of the :nitrile groups, coupling these carboxylic acidswith aromatic diazo compounds free from sulfonic and carboxyl groups,and

' finally esterifying the carboxyl group of the dyestuff thus obtainedwith alcohols at higher temperat-ures.

i Finally the processor making the new dyestuiis -may be carried out insuch away that first the lcyanoalkyl pyrazolones are converted into thecorresponding esters by saponifying the nitrile groupfand esterifyingthe carboxylgroup thus of the new monoazo dyestuffs are e. ganiline,

toluic'lines, xylidines, 3-chloro-2-toluidine, monoand dichloroanilines,o-jnitraniline, al-chloro-Z- nitraniline, s mtm-aganis cine,3-.nitro-4-tollli dine- As pyrazolone derivatives which can be "used inmaking the new dyestuffsthere may be mentioned by way .of exa-mplebio-cyano ethyl)- or l- (w-cyano-isopropyl)-3-methylor phenyl-5-pyrazolone :as well as the correspond- 5 Claims. (01. 260-463) ingcarboxylic acids and esters derived therefrom. .As suitable alcohols forthe ester form tion there may be quoted methyl alcohol, ethyl alcohol,propyl alcohol (normal and iso), the butyl alcohols, the hexyl, heptyl,and .octyl alcohols, or their technical mixtures, ethylene glycol,Lil-propylene glycol, 1,3-butylene y o1 E y" colmono-ethyl or monobu ylether, the methylcyclohexanols, p-tert. butyl-cyclohexanol,hexahydroresorcinol, tetrahydrofurfuryl alcohol.

The new dyestuffs are yellow and are par c larly suited for dyeinglacquers. Waxes and plastics, They are distinguished bya good solubilityin organic solvents, especially in aromatic hydro-- carbons and inesters. An enhanced solubility is displayed by mixtures of the newdycstuif esters, e. g. mixtures of isoheptyl and .isooctyl esters. Thedyestuffs, particularly those obtained from the diazo compounds ofo-nitraniline or its derivatives, show a very good fastness to light andsub limation. l'he shades are very clear and brilliant. f

The present invention is illustrated by the following examples, theparts being by weight; it is, however, not limited thereto:

Example 1 20 parts of o-nitranilineare stirred for one hour with 300parts of water. Now l4 parts of hydrochloric acid (19.5" Eli.) areadded; the mixture is stirredfor further '30 minutes While adding :200parts of :ice and all at once a solution of 10.5 parts of sodium nitritein 3.0 parts of water is added; then the mixture is stirred for 20minutes and the excess of nitrous acid removed by means of amidosulfonicacid. This diazo soluticn is run with stirring in a solution consistingof 22 parts of '1 cyahoethyla3emethyl5 pyraaolone, 33 parts of sodiumcarbonate, 500 parts of water and 150 parts of ice. The mixture isstirred for another hour and the dyestufi isfiltered by suction. Weightof paste: 90 parts; dry weight: 40.3 parts.

For 'saponificationand simultaneous esterific tion 4&3 parts of theabove dyestufi are added to a solution of parts of n-but-anol and l4parts of sulfuric acid .monohydrate and this suspension is refluxed for-'7 hours; after two hour all sus pended particles have passed intosolution.

After addition or zoo-parts of ice the mixture is neutralized with 10.6parts of "sodium carbonate and the excess butanol is removed by blowingin steam, On cooling as parts of butyl ester of dyestufi is very wellsoluble in lacquers, esters and aromatic hydrocarbons.

In this example n-butanol may be replaced e. g. by any aliphatic orhydroaromatic alcohol. The dyestuffs thus obtained show partly very goodsolubilities in organic solvents. The temperatures of esterification arepreferably 110-170 C. The following table shows various dyestufi estersof the type:

See. isoheptyl alcohol 112-114 Prim. isooctyl alcohol 54-56 Ethyleneglycol 92-96 Glycolmonoethyl ether 120-122 Glycolmoncbutylether 60-64Diethylene glycol 107-109 1,2-propylene glycol 115-117o-Methyl-cyclohexanol 97-99 m-Methyl-cycl-ohexanol 122-124 p-Tert.butyl-cyclohexanol 150-151 Hexahydroresorcinol 125-130Tetrahydrofurfuryl alcohol 110-112 Example 2 15.5 parts of o-toluidineare dissolved in 400 parts of water and 44 part of concentratedhydrochloric acid (195 B.) 200 parts of ice and a solution of 10.5 partsof sodium nitrite in 50 parts of water are added; the mixture is stirredfor 20 minutes and the nitrous acid is removed by means of amidosulfonicacid. This diazo solution is poured into a solution of 22 parts of 1-cyano-ethyl-3-methyl-5-pyrazolone in 400 parts of water and 200 parts ofice. After one hour the formed dyestufi is filtered by suction and themoist paste is added to a mixture of 74 part of n-butanol and 28 partsof sulfuric acid monohydrate and the suspension is refluxed for '7hours. The solution is then cooled to C. After 48 hours the main portionof the dyestuff has crystallized; M. P. 59-61 C. If n-butanol isreplaced in the esterification by glycol mono-ethyl ether 2. dyestufiester melting at 8384 C. is obtained. The dyestufi ester obtainedwhenusing glycol monobutyl ether is liquid and miscible with practicallyall organic solvents.

Example 3 7 B.). To this solution a solution of 10.6 parts of sodiumnitrite in 100 parts of water i added; after 30 minutes stirring of themixture the excess nitrous acid is destroyed by means of amidosulfonicacid. This diazo solution is added with stirring to a solution of 22parts of 1-cyano ethyl-3-methyl-5-pyrazolone in 500 parts of water, 150parts of ice, and 33 parts of sodium 4 carbonate. After one hour thedyestufi. is filtered by suction; dry weight: 41 parts.

The dyestufi is converted into the corresponding n-butyl ester by adding41 parts of the above dye-stuff to a mixture of 74 parts of n-butylalcohol and of 14 parts of sulfuric acid monohydrate and refluxing thismixture for 15 hours. Then ice and water are added, and the mixture isneutralized with 11 parts of sodium carbonate; excess butyl alcohol isdistilled ofi in vacuo. After cooling 44 parts of crystallized butylester of the 'dyestufi are obtained; M. P. 59-60 C. It is very easilysoluble in alcohol, benzene, esters and lacquers.

Example 4 20 parts of o-nitraniline are diazotized as in Example 1 andcoupled with a solution of 27 parts ofl-(w-carboxy-isopropyl)-3-methyl-5- pyrazolone in 500 parts of water,150 parts of ice and 50 parts of sodium carbonate. After one hour thedyestufi obtained is filtered by suction; dry Weight: 47 parts. Thedyestuff-carboxylic acid thus obtained is suspended in 350 parts ofn-butanol and the suspension is saturated with hydrogen chloride. Thetemperature rises to 45 C. Thereafter the solution is slowly heated to60 C. After 5 hours heating the mixture is diluted with ice and water,neutralized with sodium carbonate and the excess butanol is blown off bymeans of steam. The n-butyl ester of the dyestuff melts at -82 C. It hasa good solubility in alcohols, esters, and aromatic hydrocarbons.

1 (-.-carboxy-isopropy1)-3-methyl-5-pyrazolane is obtained by refluxingparts of l-(wcyano isopropyl) -3-methyl 5 pyrazolone with 800 parts ofconcentrated hydrochloric acid (195 B.) for 2 hours. After evaporatingthe reaction mixture in vacuo at 70 C. the residue is subjected tofractional crystallization from glacial acetic acid. 90 parts ofl-(w-carboxy-isopropyl) 3-methyl-5-pyrazolone of M. P. 209 C. areobtained.

Example 5 20.6 parts of 3-chl0ro-2-toluidine are diazotized according toExample 3 and coupled with 33.? parts of1-(y8-carboxy-ethyl)-3-phenyl-5-pyrazolone. 50 parts of dyestuff areobtained which are esterified-as described in Example 4with n-butylalcohol and hydrogen chloride for '7v hours at 80 C. The n-butyl esterof the dyestuif melts at 73-75" C.

1- (c-carboxy-ethyl) -3-phenyl-5-pyrazolone is obtained by refluxing 187parts or l-cyano-ethyl- 3-phenyl-5-pyrazolone with 900 parts ofconcentrated hydrochloric acid (195 B.) for 2.5 hours. The reactionmixture is evaporated'in vacuo and the residue subjected to fractionalcrystallization from glacial acetic acid. Yield: parts or" M. P. -186 C.

Example 6 20 parts of o-nitraniline are diazotized according to Example1 and coupled with a..solution of 33 parts of l-(B-carbobutoxy-ethyl)-3-meth'yl-5- pyrazolone in 1000 parts of'water, 200 parts of ice, 35parts of sodluincarbonate and 300 parts of potassium chloride. Themixture is stirred over night, the dyestuif is filtered by suction andcrystallized from ligroine. 40 parts of the dyestuff as described inExample 1 of the melting point 96 C. are obtained. 7

In similar manner a lacquer dyestuff melting at 132 C. isobtained'from'4-chloro-'2-nitraniline and l-(p-carbobutoxy-ethyl)-3-methyl-5-pyrazclone If 2-nitraniline is coupled with l-(flcarb-ethoxy-ethyl) -3-methyl-5-pyrazolone a lacquer dyestuif melting at 112 C. isobtained. All the dyestuffs described in this example readily dissolvein aromatic hydrocarbons and esters.

To prepare 1- (B-carbobutoxy-ethyl) -3-methyl- 5-pyr'a zolone 151 partsof l-cyano-ethyl-ii-methyl-5-pyrazolone are refluxed with 1000 parts ofconcentrated hydrochloric acid (19.5" B.) for two hours. Thereafter thereaction mixture is evaporated to dryness in vacuo; 350 parts ofnbutanol areadded to the residue and the suspension is saturated at 40C. with hydrogen chloride. After hours the ammonium chloride formed isfiltered off, the butanol is distilled off in vacuo, and the remainingsyrup is dissolved in allLCO-ORI wherein R stands for an aromaticradical of the benzene series free from sulfonic and carboxyl groups,alk stands for an alkylene radical, 0R1 stands for the radical of analcohol, and X stands for a radical of the group consisting of alkyl andphenyl.

2. Monoazo dyestuffs corresponding to the general formula:

. Ail-70.031

wherein R stands for an aromatic radical of the benzene series free fromsulfonic and carboxyl groups, all; stands for an alkylene radical, andCR1 stands for the radical of an alcohol.

3. Monoazo dyestuffs corresponding to the general formula:

wherein R stands for an aromatic radical of the benzene series free fromsulfonic and carboxyl groups, and CR1 stands for the radical of analcohol.

4. Monoazo dyestuffs corresponding to the general formula:

wherein R stands for an aromatic radical of the benzene series free fromsulfonic and carboxyl groups, and CR1 stands for the radical of a butylalcohol.

5. The monoazo dyestuff of the formula:

N hHaC O. O C(Hohi) being a yellow crystalline compound melting at 96-98C.

HAN S-FRANK PIEPENBRINK. OTTO BAYER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,060,563 Fischer Nov. 10, 19362,289,210 Reynolds et a1. July '7, 1942

5. THE MONOAZO DYESTUFF OF THE FORMULA: